Background (Lake Roosevelt Fisheries Evaluation Program (1994-043-00)

The Lake Roosevelt Fisheries Evaluation Program (BPA NO. 1994-043-00; previously referred to as the Lake Roosevelt Data Collection Program) is the result of a merger between the Lake Roosevelt Monitoring Program (BPA No. 1988-063-00) and the Lake Roosevelt Data Collection Program (BPA No. 1994-043-00).  The two projects combined efforts in 1996 to continue work historically completed under separate contracts and to identify data needs for development of biological and integrated rule curves for Lake Roosevelt as required in the NWPCC Fish and Wildlife Program (10.8B.5).  These projects merged because each required support staff and data from the other project to complete deliverables.  

The Lake Roosevelt Monitoring Program began in July 1988.  The intent of the project was to: 1) determine the status of fish stocks in Lake Roosevelt before construction of hatcheries and habitat improvement efforts; 2) Evaluate contributions of habitat improvement projects and hatcheries to Lake Roosevelt fisheries; and 3) recommend hatchery out-planting strategies which maximize harvest of kokanee and rainbow trout and egg collections from kokanee while minimizing impacts to wild populations.

Lake Roosevelt Monitoring Project submitted annual reports to BPA for each year from 1989 through 1995 (Peone et al. 1990; Griffith and Scholz, 1991; Griffith et al. 1995; Thatcher et al. 1996; Underwood and Shields, 1996a; Underwood et al., 1996 a and b (sections 2 of Lake Roosevelt Fisheries and Limnological Research 1994 and 1995 Annual Reports) and five supplemental reports (Scholz et al. 1992 and 1993, Tilson et al., 1996a, b and c).

In 1991, the Lake Roosevelt Data Collection Project began operating under the Lake Roosevelt Monitoring Project number 1988-063-00.  The purpose of the Data Collection Project was to assist the resident fish workgroup of the System Operation Review with the development of the EIS.  The Project collected data on biotic indices of Lake Roosevelt believed to be affected by lake operations.  Those indices included zooplankton density and biomass, water quality and fish growth and entrainment.  In 1994, the Data Collection Project was given a separate contract and project number.

The Lake Roosevelt Data Collection Project submitted annual reports to BPA for each year from 1993 through 1995 (Voeller 1996, Shields and Underwood, 1996a and b (sections 1 of Lake Roosevelt Fisheries and Limnological Research 1994 and 1995 Annual Reports).

The 1996, 1997, 1998, 1999, 2000, 2001 and 2002 annual reports for the Lake Roosevelt Fisheries Evaluation (Data Collection) Program (Cichosz et al. 1997, 1999, Spotts et al. 2002, Shields et al. 2002, McLellan et al. 2003, Lee et al. 2003, Scofield et al. 2004, Fields et al. 2005) have been submitted to BPA.  Completion of the 2003 annual report is currently in progress.  A draft will undergo a final review by the Lake Roosevelt co-managers and be submitted in August of 2005.  In addition, Tilson et al. (1999), Baldwin et al. (1999), and McLellan et al. (1999) submitted 1998 annual reports under subcontracts to the Lake Roosevelt Fisheries Evaluation (Data Collection) Program. Other subcontractor reports include McLellan and Scholz (2001), McLellan et al. (2002), McLellan et al. (2001), McLellan and Scholz (2002), McLellan and Scholz (2003), Baldwin and Polacek (2002) and Baldwin et al. (2004).  Completion of the 2003 & 2004 annual reports and associated data review and analyses are in process, and will be completed during the 2006 fiscal year.

Water Quality Surveys:  
Baseline water quality sampling from 1988-1996 occurred monthly at nine or more locations.  In 1997, we enhanced existing methods and increased sampling periodicity and intensity to provide data necessary for ecosystem modeling.  Water quality data were collected using a Hydrolab and water sample grabs analyzed by the Spokane Tribal Laboratory.  Water grabs consisted of composite samples collected from the aphotic and photic zone.  Laboratory analyses provided baseline information for common analytes associated with limnological studies.  Chlorophyll a concentrations, phytoplankton speciation and bio-volume were also collected as part of the bi-weekly water quality monitoring.  Water quality studies suggest Lake Roosevelt is generally isothermal with weak temperature gradients during the summer and early fall (Cichosz et al 1998 and 1999).  Nutrients are low in concentration, suggesting phytoplankton production is nutrient limited.  Since 2002, water quality sampling has been reduced to 5 sites seven months a year and samples are collected using an integrated sampling tube and Hydrolab.

From 1988 to 1996, zooplankton sampling was conducted at 9 index locations during three seasons.  In 1997, in an attempt to better understand the population dynamics of zooplankton and the effect of hydro-operations and other biological, chemical and physical parameters on density and community structure, zooplankton collection was increased to twice per month at eleven standardized monitoring stations.  This sampling, combined with the water quality sampling, was designed to develop a comprehensive database to be used in modeling efforts.  

The natural heterogeneity of zooplankton populations and the high flow observed in many reservoirs make determination of zooplankton production rates, an essential component of the Lake Roosevelt model, extremely difficult.  As a result, additional efforts to define relationships between water quality and production within the various trophic levels was initiated  The purpose of the study was to determine what effects hydro-operations have on the zooplankton population, how zooplankton perform in the absence of zooplantivorous fish, and to track individual population cohorts in an ambient reservoir setting.  In situ zooplankton corrals were placed at three sites along the length of the reservoir.  The corrals were deep enough to allow diel vertical migrations with a mesh size large enough to allow phytoplankton to move freely in and out of the corral, but small enough to contain most zooplankton species.  This method allowed improved understanding of zooplankton production potential and realized population growth rates, as well as allowed us to relate water retention time, with other environmental factors, to zooplankton growth, abundance, and community structure (Cooper and Black 1999).  This information will be vital to calibrating and verifying the models.

Modeling:  
Dr. Scott Wells of Portland State University is currently developing an ecosystem-based model for Lake Roosevelt (CE-QUAL-W2 water quality model with a water routing model linked to address flow).  Dr. David Beauchamp of the University of Washington is developing a bioenergetics model to be linked with the CE-QUAL-W2 water quality model.  The increased level of data collection began by the Lake Roosevelt Fisheries Evaluation (Monitoring) Program in 1997 is being used to define trophic interactions, the effects of hydro-operations, and the effects potential management actions may have on the Lake Roosevelt ecosystem.  Baldwin et al. (1999) initially used zooplankton density to predict the carrying capacity of kokanee in Lake Roosevelt based on a Wisconsin bioenergetics model. Initial runs suggest that Lake Roosevelt could support millions more kokanee than what is now stocked into the lake.  Dr. Beauchamp of the University of Washington will continue this work in 2004-05, working with Dr. Scott Wells of Portland State University to link the bioenergetics with the water quality model to further explore these questions.

Benthic Surveys:  
Macroinvertebrate density is an important component when considering the use of bioenergetics models and considering methods to enhance the complexity of the ecosystem.  Benthic macroinvertebrates were sampled in littoral areas in 1998 and 1999 in an attempt to verify previous reports indicating macroinvertebrate levels are severely depressed in Lake Roosevelt (Bortleson et al. 1994, Voeller 1993 and Griffith et al. 1995).  The 1998-1999 study used a ponar dredge to collect samples at sites established in previous studies (four to nine index stations, stratified by elevation).   Preliminary results from the 1998-99 study (Miller, personnel communication, Colville Confederated Tribes) indicate macroinvertebrate levels appear to be similar to those reported by earlier studies, low macrovertebrate abundance in the littoral zone of Lake Roosevelt.  These reports are pending from the Colville Confederated Tribes.

Fisheries Surveys:  
Since 1988, the Evaluation Program has collected fish once in spring, summer, and fall at ten index stations throughout the reservoir (modeled after Beckman et al., 1984).  Standardized fish surveys consist of electrofishing and gillnetting (vertical and horizontal; Cichosz et al. 1998, 1999, Fields et al. 2005).  Meristic measures, bony structures, and stomach contents are collected to monitor growth, age structure and food preference.  This information is expanded to monitor potential competitive interactions amongst wild and hatchery origin fish based on changes in growth, age structure, and diet overlap.  The primary purpose of this activity is to measure shifts in fish community structure, identify changes in growth rates of fish, and determine fish feeding behaviors, which assists managers with determining whether hatchery fish are interacting with wild fish, growth has changed over time, and whether food is limiting.  Lake Roosevelt is a maturing reservoir and long-term trend data provides information on changes in the structure and composition of the fish community within the reservoir over time.  Understanding long-term changes potentially provides insight into how the fish community is evolving.  This information is also used to determine harvest regulations and hatchery release numbers.

The Evaluation Program has had limited success with collecting kokanee by gillnet or electrofishing.  In response to this problem beginning in 1997, mobile hydroacoustics were deployed in Lake Roosevelt as a means to obtain distribution and population estimates of the mid-lake kokanee.  The use of hydroacoustics allows us to track kokanee populations, identify periods when kokanee are vulnerable to entrainment, study fish dispersal behavior on recently released hatchery kokanee and observe changes in kokanee locations with changes in hydro-operations.  This information, in conjunction with the fixed hydroacoustics data collected at Grand Coulee Dam by the Chief Joseph Kokanee Enhancement project, is currently being used to develop hydro-operation recommendations that minimize entrainment.

Mark-Recapture Studies:  
Approximately 20,000 to 60,000 net pen rainbow trout have been marked with anchor tags annually and released in Lake Roosevelt.  Tagged fish are recovered through creel surveys, electrofishing, gillnet surveys and voluntary angler returns.  Tagging studies provide information on performance of hatchery-origin fish, growth rates, dispersion from release sites, and an index of entrainment.  Tagging studies have shown releasing net pen rainbow trout after June 1 while the lake elevation is above 1260 greatly reduces entrainment (Cichosz et al. 1999).  The net pen program now follows this recommendation.  In the past, net pen fish were released in May when lake elevation and water retention times were low.

Beginning in 1999, and continuing through 2004, tag studies have also focused on stock performance.  Paired release groups of Phalon Lake redband and the historically used Spokane stocks (a coastal derived stock) are being evaluated in an effort to replace the Spokane Stock with one more closely related to the wild indigenous stocks of Lake Roosevelt and other regions of the upper Columbia River.  Factors considered in stock performance are genetic introgression with indigenous rainbow trout of the upper Columbia River, impacts to downstream salmonids (genetic and competition-based), and in-lake feeding behavior.  

Limitations on the availability of Phalon Lake redband trout have prompted managers to examine triploidy as a possible alternative to shifting the Lake Roosevelt rainbow trout program to Phalon Lake redband trout.  Paired release studies to compare triploid and diploid Spokane stock rainbow trout will assess reservoir feeding behavior, growth and recruitment to the fishery.   Initial assessment of the triploidy process used by the program indicates a triploidy success rate of approximately 98%.  This implies genetic introgression with indigenous rainbow trout in the system is likely limited.  In 2004-05, a complete analysis of tag data collected from 1988 through 2003 was conducted to determine the most successful release strategies and stocks.  Significant findings will be submitted to a peer-reviewed scientific journal.

Mark and recapture methods are also used to assess the program goal of establishing a self-sustaining Lake Roosevelt kokanee population.  From 1991 to 1993, approximately 500,000 fry and yearling kokanee were subjected to imprinting chemicals at different life stages, coded wire tagged as separate test groups, and released into the lake.  Initially, this study was designed to determine which imprinted life stage expressed higher return rates to egg collection facilities (Scholz et al. 1993, Tilson et al. 1993 and 1994).

Analysis of data collected early in the programs history indicated that the majority of returning kokanee resulted from yearling releases, while very few fry returned (Tilson et al. 1993 and 1994).  In 1994, the decision was made to release primarily yearling kokanee rather than fry.  Recent studies have focused on the need to use different fish stocks.  Initial study results suggest that fish transferred to Sherman Creek Hatchery prior to June appear to imprint to Sherman Creek Hatchery water prior to release, while kokanee yearlings transferred to Sherman Creek after June are less likely to imprint (Tilson et al 1999).  The performance of upriver kokanee stocks compared with other kokanee stocks is being analyzed as fish are available for release into Lake Roosevelt.  Current work utilizes thermal otolith marking and fin clipping to identify various kokanee release groups.

Managers currently believe a large percentage of wild kokanee collected from Lake Roosevelt are migrants from British Columbia.  These are relatively large-bodied kokanee that are an apparently self-sustaining wild component of the fishery, however, current numbers are too low to sustain current fishing pressure in the reservoir.  In early 2004, the artificial production program released 300,000 upriver kokanee fry into Big Sheep Creek.  The fish were marked with a thermal otolith mark and released to examine the effectiveness of mimicking more natural conditions observed in upriver tributaries.  This differs from earlier fry vs. yearling studies because the release strategy is very different, and because the number of fry released is much greater now compared with the earlier studies.  We plan to continue to review the effectiveness of this strategy.

Creel:  
The creel survey first began in 1988 and was a two-stage probability-sampling scheme used to determine annual fishing pressure, catch-per-unit-effort, and sport fish catch and harvest by species in Lake Roosevelt.  This survey was designed according to methods described by Lambou (1961 and 1966) and Malvestuto (1983).  From 1988 to 1998 the surveys were conducted by three creel clerks at access points approximately 21 days a month, 12 months a year.  From 1999 to early 2004, the survey was limited to 9 months of the year to reduce costs.  The creel is used to estimate the number of wild and hatchery origin fish harvested, identify temporal and spatial overlap of wild and hatchery fish, and determine growth and size of fish harvested.  Creel surveys are essential to evaluating hatchery performance and achievement of biological objectives.

In 2003, we had a biometrician begin to review the old creel design, as recommended during the Independent Scientific Review process.  Early in 2004, the biometrician developed new creel protocols that will allow the program to more efficiently, effectively and completely collect and analyze creel data beginning in fiscal year 2004.

Additionally, due to the unique character and large angler pressure events that occur on Lake Roosevelt, the program has begun supplemental creel data collection.  These methods include one weekend each to collect data from the Two Rivers Trout Derby and the Governors Cup Walleye Tournament, one week per year collecting data via a test fishery targeting kokanee and angler diaries have been distributed to efficient, dedicated Lake Roosevelt anglers that commonly collect kokanee and rainbow trout throughout the spring and summer.  

Habitat:  
A habitat use and availability study commenced in 1997.  This study began by mapping habitat types at nine index sites that were stratified by embayment, shear wall, and other categories.  These sites are also examined during drawdown periods (de-watered) to measure substrate type, lake bottom slope, and structure.  Once re-watered, fish surveys are conducted over habitat units at various times of the year.  Collected information is being used to determine habitat use.  At the same time, a GIS bathymetric map with overlays of habitat characteristics is being developed to estimate the availability of habitat throughout the reservoir.  The GIS map will be able to predict the availability of habitat or the lack thereof with each incremental foot of drawdown.

Accomplishments:  
Co-managers and project partners (Washington Department of Fish & Wildlife, Colville Confederated Tribes and Eastern Washington University) have worked cooperatively to develop management recommendations and are developing a Lake Roosevelt Fisheries Guiding Document to detail management strategies over the next five years.  Examples of adaptive management strategies resulting from this project include revisions in hatchery release strategies for kokanee and rainbow trout.  Rainbow trout release timings have similarly been altered with beneficial results based on mortality and entrainment studies conducted under this project.  Additionally, the Program has compiled long-term data in databases that are maintained for project use, eventual inclusion into the JSAP database and calibration of the Lake Roosevelt Ecology Model and we have completed Annual Reports 1989-2002 (reviewed by project participants).

Year 2006 In Brief:  
This year's Lake Roosevelt Fisheries Evaluation Program Statement of Work continues previous work that focuses efforts towards maintaining reduced data collection efforts and increased data analyses and report writing efforts, both to complete deliverable schedule and for publication in peer reviewed journals.  The work proposed for 2006 includes the continuation of work such as water quality, primary productivity, zooplankton, creel and fishery surveys, pelagic fish via hydroacoustics, habitat mapping and utilization, and bioenergetics modeling.  Moreover, we plan to continue development and initialization the CE QUAL-W2 water quality model for Lake Roosevelt, including incorporation of the bioenergetics model and a water routing model into CE QUAL-W2.  Work on the model is expected to continue and be completed in the summer of 2006.

We also plan to finalize the fisheries management guiding document for Lake Roosevelt, initially developed based on past management findings, research, and local manager input.  The plan will be refined based on model outputs to identify lake operations and management actions, which have the highest likelihood of maximizing the Lake Roosevelt fishery and other resources within and outside of the lake.

Program Goals:

• Develop an informed fisheries management guiding document with mitigation and water management recommendations that maximizes the Lake Roosevelt fisheries while providing for the needs of other resources downstream.

• Monitor and evaluate the effects of stocking fish from Sherman Creek and Spokane Tribal Hatcheries on the ecology of Lake Roosevelt.  Also, identify stocking strategies that maximize angler harvest and collection of rainbow trout and kokanee salmon eggs.



Hydroacoustics / Bioenergetics Specifics (WDFW):
The Lake Roosevelt Monitoring/Data Collection Project has been collecting physical, chemical, biotic, and abiotic data since 1988 (Peone et al. 1990; Cichosz et al. 1997; McLellan et al. 2001; McLellan et al. 2002).  During this project it became clear that efforts to stock kokanee into Lake Roosevelt were not meeting the creel and spawner return goals of managers (Cichosz et al. 1997).  Data gaps also existed because most monitoring efforts focused on the littoral zone and were missing the limnetic oriented fish including kokanee, rainbow trout, burbot, and lake whitefish.  Thus in 1998, the Washington Department of Fish and Wildlife (WDFW) began a limnetic sampling regime for Lake Roosevelt to address specific questions regarding limiting factors to limnetic fish populations.  The information in this report should be considered in combination with the efforts of other Lake Roosevelt Fisheries Evaluation Program participants including the Spokane Tribe of Indians (STI), Colville Confederated Tribes (CCT), and Eastern Washington University (EWU).

Limiting Factors

Many factors can contribute to poor survival of fish populations in a reservoir.  Typical lake abiotic conditions and biological interactions are altered and exacerbated by reservoir fluctuations.  Potential factors effecting survival include inadequate spawning habitat and rearing habitat, poor egg to fry survival, low food supply, high predation, over-exploitation, emigration, entrainment, and unfavorable physical and chemical conditions.  The primary management goal for Lake Roosevelt fisheries was the successful recruitment of hatchery-reared salmonids to the fishery.  Additionally, kokanee were to return at age 3 or 4 to egg collection facilities to establish a self-sustaining hatchery program.  We did not address spawning and early life history survival because the hatcheries were producing yearling fish.  Previous studies have shown low exploitation of stocked salmonids, although harvest goals have been achieved for rainbow trout on a regular basis (Cichosz et al. 1997,1999).  Additionally, WDFW has conducted analysis on entrainment, predation, and food limitation (Baldwin et al. 2003).  An important component of these analyses is understanding the distribution, abundance, and diet of limnetic fishes.
Fish distribution and habitat use are restricted by fixed physiological constraints, which limit the geographical distribution of particular species.  Fish can cope with sub-optimal conditions in certain systems using behavioral adaptations such as occupying thermal refuge or foraging for short periods in lethal environments (Rahel and Nutzman 1994; Snucins and Gunn 1995).  It is important to relate fish distribution to the physical and chemical domain in which they are operating to identify spatial or temporal stresses.  Conversely, if fish are occupying physical zones that are sub-optimal, then behavioral mechanisms to maximize feeding or avoid predation may be identified (Clark and Levy 1988; Luecke and Teuscher 1994).
Food limitation and competition can limit fish populations in lakes and reservoirs (Schneidervin and Hubert 1987; Griffith 1988; Persson and Grenberg 1990; Tabor et al. 1996).  Rainbow trout and kokanee commonly rely on zooplankton, specifically large daphnia, as a major food source in many western lakes and reservoirs (Galbraith 1967; Eggers 1982; Schneidervin and Hubert 1987; Beauchamp 1990; Beauchamp et al. 1995; Paragamian and Bowles 1995; Teuscher and Luecke 1996; Luecke and Teuscher 1994; Tabor et al. 1996; Cichosz et al. 1997,1999).  When oligotrophic systems such as Lake Roosevelt are artificially supplemented with large numbers of planktivores, there is potential to overexploit zooplankton biomass (Dettmers and Stein 1996).  Several approaches have been used to evaluate food limitations in fish populations.  Fish expressing slow growth and low relative weight, when compared to a regional standard, were considered food limited in many studies (Wege and Anderson 1978; Murphy et al. 1991; Marwitz and Hubert 1997).  Small invertebrate prey size has also been used to indicate food limitation for fish predators (Mills and Forney 1983; Crowder et al. 1987). However, in large reservoirs, averages and standards may not apply due to geographic and biological diversity both within and among systems.
The goal of the bioenergetics portion of this project will be to add a fish bioenergetics component to the CE-QUAL-W2 hydrodynamic and water quality model being developed for Lake Roosevelt by Dr. Scott Wells and his team. In its final form, this additional capability will ultimately enable the model to examine spatially-explicit consumption demand and growth response by specific size/age classes of fish species residing in the reservoir. Furthermore, the model would provide estimates of how growth and consumption would change in response to changing food supply and thermal regimes resulting from different reservoir operating conditions. The role of this pilot study will be to explore how bioenergetics functions and perhaps fish foraging model(s) can be built into the hydrodynamic and water quality model.
The bioenergetics functions and parameters for kokanee (Beauchamp et al. 1989) and rainbow trout (Rand et al. 1993) will be provided to the CE-Qual-W2 modeling team for integration into their existing modeling architecture. The bioenergetics model is an energy/mass balance equation that operates on a daily time step and estimates the amount of consumption required to grow an observed or specified mass over some time interval, given an initial body mass, and either an observed, specified, or modeled thermal experience and diet composition for the consumer. If consumption estimates can be specified or derived (e.g., from foraging models), then the bioenergetics model can estimate the growth over the interval of interest.
We will examine temporal patterns in temperature, zooplankton density and distribution, and fish growth and diet (juvenile kokanee and rainbow trout) from an existing 2002 draft report from the Spokane Tribe to determine appropriate spatial-temporal bounds and zooplankton density ranges for modeling fish behavior and physiology. Size frequency distributions for key zooplankton taxa will be used to determine how to convert zooplankton biomass estimates generated by CE-QUAL-W2 into numerical or biomass densities of exploitable biomass for fish, based on size and species selectivity of kokanee and rainbow trout and the spatial-temporal variability in size distributions of key zooplankton in the reservoir.
We will briefly explore the feasibility of incorporating fish foraging models for planktivores (Stockwell and Johnson 1997, 1999; Koski and Johnson 2002) and piscivores (Beauchamp et al. 1999; Hardiman et al. 2004; Mazur and Beauchamp 2003 and in prep.) into this approach. If successful, the CE-QUAL-W2 model would predict the thermal regime and temporal-spatial distribution of zooplankton that would then drive the distribution, consumption, and growth of planktivorous fish like kokanee and rainbow trout. However, these fish are vulnerable to larger predatory fish, and their movement and distribution patterns could deviate from one that maximizes growth to an alternative strategy that optimizes growth versus predation risk under certain prescribed ecological constraints. It will be beyond the scope of this pilot study to do more than a cursory exploration of this approach due to limited time and funds; however, the possibility of linking these upper trophic-level processes into a comprehensive model based on hydrodynamic processes through multiple trophic levels holds enormous potential for understanding and managing Lake Roosevelt and a multitude of other lakes and reservoirs.